JAJS640H September 1999 – March 2024 LM1084
PRODUCTION DATA
A simple constant current source with protection can be designed by controlling the impedance between the lamp and ground. The LM1084-ADJ shown in Figure 7-7 makes use of an external TTL or CMOS input to drive the NPN transistor. This pulls the output of the regulator to a few tenths of a volt and puts the part into current limit. Releasing the logic will reduce the current flow across the lamp into the normal operating current thereby protecting the lamp during startup.